Recovery of bismuth



June 25, 1940- .1. o. BETTERTON 4Er Al. 2,205,387

RECOVERY OF BISMUTH Filed Aug. 28. 1939 Fon Eff/N50 INVENTORS PatentedJune 25, 1940 UNITED s'rArEs PATENT OFFICE RECOVERY 0F BISMUTH Jesse 0..Betterton and Ym'ii E. Lebedeil',

Metuchen, N. J., asslgnorsto American Smelting and Relining Company, NewYork, N. Y., a corporation of New Jersey Application Augustfzaisss,serial Ne. 292,252

' 1o calms. (cl. 15-10) content. The drOSS may then be ieached With atwo metals can be effected. It has been found solution of sulphuric acidto dissolve the alkali,' that such elassineation een be accomplished lnl alkaline earth saltsv and yield a bismuth lead many different mannersas, for example, by el-dlresidue suitable for smelting to crude bismuthnarysereenmg or the use of such standard appametal and SbSequent reningt0 Dlile bismuthratus as the Callow cone, Hardinge drum classi,- zoWhile pressing and liquating will materially fier, vvllney table and thelike. loyer the lea-.d Content 0f gnualklillee bismuthlde i Followingthe separation 0f the black liquor, dross, nevertheless, considerablelead will remain containing the bismuth from the lead residue, and aSthe bismuth t0 lead ratio 0f thedlOSS iS the former is treated,preferably by ltration, Substantially llnaieeted'by theleaching Stell'aS to separate the bismuth from the liquid. The 25 -above described, allof the remaining lead must nlm-ate free from bismuth may be returned to'be removed by Subsequent ysmeitins or rening. treat further quantitiesofalkaline bismuthide Operation. dross and the bismuth residue processedfor the The present invention iS based upon the 'diS- recovery of purebismuth. The lead residue may every that when an alkaline bismuthided1'0SS be returned `to the process for concentration of 30 Containinglead is reacted upon by Water, the its.f depleted bismuth content asalkaline bis-v bismuthand leadjdare transformed into a state m thldedross and Subsequent treatment in ae.. susceptible ofreadyf'classiflcation. Actual operacordel-lee with the invention. tionshave demonstrated that it is possible. by Instead of using just plainwater in reacting Simple elaSSiCatiOni-t COIlSiStelltly Obtain 90% uponthe bismuthides, dilute acid solutions may 35 or more of the totalbismuth in One DrOdllCt 00nbe employed asneltherthe bismuth nor the leadtaining only a fraction of the lead present in will be substantiallyaffected at the low temperathe dross p rior to reacting the latter withwater. tures normally employed. Att-,he same time, how- By thasfavorably altering the bismuth to lead ever, the presence olethe acidwill accelerate the' ratio, the present invention constitutes a markeddecomposition of the bismuthides, especially when improvement in theart. treating low grade dross. Typical examples of o The invention iS,nfexemlrse, applicable to the acid that may'be added to the water aresule treatment of praeticall`y=any 0f the alkaline biS- phuric andhydrochloric which convert the al- -muthide drosses obtained. bytreating bislnilthkaline content of the bismuthides into sulphates leadalloys with appropriate alkali, alkaline earth, and chlorides,respectively. 5

'I'his invention relates to the production of bismuth and particularlyconcerns certain improvenients in the concentration a bismuth frombismuthide drosses.

It is well known that when a bismuth lead alloy of alkali, alkalineearth'uorides and/or chlorides and liquated therebyv materially loweringits lead or rare earth metal debismuthizing reagents. However, forthebest results, the bismuth contentof the dross should be relatively Ahighandcare should 'be exercised to prevent oxidation of the dross priortoits treatment with water. A

ndross produced through the use of calcium and* present invention. y

n d recovery of In practising the invention, the alkalinebismuthidedross is reacted with water in a suitable vessel andagitated untilcompletely decomposed. Assuming calcium and vmagnesium to be thereagents employed in forming the dross, its decompositionA may be.expressed bythe following equations:

The elemental bismuth resulting from the re'- action of the bismuthidesin the dross with water imparts a black color to the liquid and is insuch a liinely-divided state as compared to the partlcles of lead thatan eiilcient classification of the `the processof the invention. l I'hatalkaline bismuthide-lead drosses are readily amenable to classiiicationfollowing reaction with" water is amply'evidenced by the followingspecic example.

In this instance'310 parts by weight oi pressed and liquated bismuthldedross assaying 48.93% lead. H40.31% bismuth, 4.93%icalcium and 5.43%

magnesium was agitated with' 150 volumes or water for iour hours.Immediately thereafter the black liquor containing the bismuth Awasdecanted from the heavier insolubles., The liquor was then ltered andthellter cake washed with water, there being produced 277 partsby weightof wet cake and 1315 volumes of ltrate containing 0.89 gm,/l. calcium,0.04 gmv./l. lead,

' a trace of magnesium and no bismuth. The bismuth lter cakeafter dryingfor 16 hours at 105 C. was 180 parts by weight and had a bismuth to leadratio of ove'r 4:1 as compared to a ratio of 1.2:1 for the dross priorto its treatment in accordance with the `invention.

It will be apparent that ingitsbroader aspects the inventioncontemplates treating an alkaline bismuthide lead dross with an aqueousreactantalkaline bismuthide dross which comprises decomposing ,the drossin the presence of water to yield inely-divided elemental bismuth in theform of a liquor containing practically the entire bismuth content ofthe original dross, subjecting the liquor and decomposition residue to aclassitying operation toeseparate the liquor from at least the majorpart of the residue, and separatin'g the bismuth from the liquidcomponent of the liquor. Y

3.' The process for recovering bismuth from an alkaline bismuthide drosswhich comprises decomposing the dross by reaction with a dilute acidsolution to yield iinely-divided elemental bismuth in the form o! aliquor containing practically the entire bismuth content of the originaldross,subjectin'g the liquor and decomposition residue/to a classifyingoperation to separate the liquor from at least the major part of theresidue, .and separating the bismuth from the liquid component of theliquor.

4. The process for obtaining bismuth from a water-reactant alkalinebismuthide dross which comprises decomposing the drosswith water toyield thebismuth in a iinely-divided state Fand forming a liquor` in'which there is suspended substantially the entire bismuth content ofsaid dross, separating the vliquor from heavier waterinsolubledecomposition residues, and recovering the bismuth irom said liquor.

" 5. The process for Vrecovering bismuth from bismuth-lead alloys whichcomprises concentrating the bismuth as a water-reactant alkalinebismuthide dross, decomposing said dross in the presence of water toconvert the bismuth content thereof to finely-divided elemental bismuth,re-

'1. The process for producing bismuth which comprises decomposing aquantity of alkaline bismuthide-lead dross in the presence of water,

, classifying the resultant material into a black liquor containing thebulk of the bismuth and a lead residue relatively low in bismuth,ltering said liquor, employing the ltratein the decomposition ofanadditional quantity of dross, and

t covering said iinely-divided elemental bismuth as processing thebismuth residue from thetiiltration step to yield rened bismuth. A

8. The process for treating a bismuth-lead alloy which comprisestreating said alloy with appropriate reagents from the alkali, alkalineearth and rare earth groups of metals to concentrate the bismuth in analkaline bismuthidelead dross, treating vsaid dross inA the presence ofwater to decompose thebismuthides and form a liquor containing thebismuth in finely-divided form, eiecting a further concentration ofbismuth by classification of the bismuth liquor from the lead residues,and separating the liquor from g its bismuth content.

9. The process for obtaining bismuth-lead alloy which comprises`eil'ecting an initial concentration of the bismuth as an alkalinebismuthide-lead dross, eifecting a further concentration of the bismuthby fusion of the dross with alkali, alkaline earth halides and liquationof the fused mass, eiecting a still further concentration of the bismuthby reacting the salt residue containing the alkaline bismuthides withwater and separating the bismuth-bearing liquor from the bulk of thelead present in the salt residue, and recovering bismuth from saidliquor.

10. The process for recovering bismuth from drosses containing alkalinebismuthides which comprises reacting same with a dilute acid solution,and then mechanically classifying the rebismuth from a 5 action productsto yield a'high-bismuth concentrate.

